Rotary rock drills



Sept, 18, 1956 J. A. E. BURLS ROTARY ROCK DRILLS 2 Sheets-Sheet 1 Filed Dec. 30, 1952 United States Patent ROTARY ROCK DRILLS John Albert Edward Burls, Frinton on;Sea, England, as-

signor to The Cementation Company Limited, London, England, a British company This invention relates to rotary rocl; drills and is concerned with drills of the type, in which there is a; drill body. carrying several drill bits arranged to turn about their axes, the body being adapted for attachment to drill pipes, which can be rotated to turn the drill body about its axis.

According to the invention, there is provided a rotary rock drill of the type specified, wherein; means are arranged to apply impacts directly or indirectly to the drill bits, the latter being connected to said means in such a way that upon rotation of the bits during a drilling operation the necessary energy for the impacts is. imparted to said means from the rotating drill bits.

For a better understanding of the invention and to show how the same may be carried intoefiiect, reference will now be made to the accompanying drawings in which:

Fig, 1 is a sectional elevation of the rock drill,

Fig. 2 is a diagrammatic view to a smaller scale of the drill body,

Fig. 3 is a diagrammatic view of the drill body in, a different operative position, and

Fig. 4 is a sectional elevation of another embodiment of rock drill,

Fig. 5 is ahorizontal, sectional. view taken along the line 5-5 of Fig. 1,

Fig. 6 is a horizontal sectional view taken line 6--6 of Fig. 1, and

Fig. 7 is an enlarged detail view showing the driving connection between one of the drill bits and a crown gear on a member within the drill body of Fig. 1.

In the constructional form as shown in Figures 1 to 3, the drill body generally indicated by 1 is of substantially cylindrical shape. One end of the body has an integrally extending boss 2 which is. externally screwthreaded. to receive one end of a drill pipe 3 (indicated in broken lines). The drill body 1 has an axially extending bore which widens towards the bit supporting end to form an internal chamber as shown in the drawings. The drill body is divided into two portions 4 and 5 along a horizontal plane perpendicular to the axis of the body and passing through the internal chamber. The annular surface of each body portion 4 and 5 is formed with sets of circularly extending long wedge-like teeth 6 and 7 respectively (Figs. 2 and 3). When the portions 4 and 5 are turned relative to each other, they are axially displaced from one another until the crests of the two sets of teeth 6 and 7 just pass one another whereupon the portions 4 and 5 move rapidly together. The body portion 4 is intended to be rotated in the direction of the arrow shown in Figures 2 and 3.

The part of the internal chamber which lies within the portion 4 is of non-circular cross-section. The part of the chamber lying in the portion 5 is circular in section. The body portion 5 has at its lower end several radially extending supports for rock bits 8. The bits 8 are of substantially standard type and are frusto-conical in shape with teeth disposed on the external curved suralong the V the upper sides of the drill bits 8 and the mouth of the internal chamber in the drill body 1. The support member bears against an appropriately prepared shoulder 1Q on the lower drill body portion 5, and the annular support member has a reduced sleeve-like extension 11 which fits within the chamber in the body portion 5. The,

sleeve 11 is continued into. the internal chamber in the drill body portion 4, being in this locality non-circular so as to fit the non-circular internal chamber. Above the non-circular portion.1 2 of the sleeve 11, the latter is considerably reduced in external diameter and con.- tinues as a tubular extension 1 3 which fits within and passes through the axial bore of the boss 2, and emerges at the top end thereof. At the upper end of the tubular part 13 there is a stop nut 14, and between the stop but 14 and the upper face of the boss 2 a spring 15 is located which serves, to retain the assembly when the. drill is not in use.

The annular support member 11 has an annular series of teeth 16 forming a crown gear co-operating with gear teeth 17 extending around the outer ends of the rotary drill bits 8, and the annular snpport member 11 may thus be regarded as. a crown wheel and the body portion 4 and the sleeve 11 as a, driving unit. The teeth 17 on the bits also act as cutting teeth during a boring operation. A bore 23 is provided in the sleeve 11 for allowing liquid pumped down to the drill to. lubricate. the surfaces between the sleeve 11 and the body portion.

In the employment of the drill described, the drill pipes are progressively assembled as drilling proceeds, with the lowest pipe 3 firmly gripping the boss 2 of the drill body. The drill pipes are rotated with the rotary rock; bits 8 in contact with surface to be drilled. The drill pipe 3 is a rotary direct drive which causes the body portion. 4. to be rotated. The non-circular part 12 of the sleeve 11 is, therefore, correspondingly rotated. The member 5, however, is free to rotate with respect to the circular portion of sleeve 11 on which it is mounted. As sleeve. 11 is rotated by. member 4, crown gear 16 drives the gears 17 of the roller bits 8. to elfect rotation of the latter However, since the roller bits 8 are in rolling contact with the rock formation being drilled or bored, rotation of the bits 8 causes the. former to roll upon the rock formation and effect rotation of the member 5. The gear ratio of gears 16 and 17 is selected so that rotation of member 5 produced in the manner described above while being in the same direction as the rotation of member 4 will be at a slower speed. Accordingly there will be relative rotational movement between the body members 4 and 5. The long wedge-like teeth 6 and 7 existing on the contacting surfaces of the body portions 4 and 5 are thus caused to ride over one another as inclined planes. As the teeth crests move towards register, the drill body portion 4 causes the drill pipes to be lifted. After the crests pass one another, the portion 4 falls upon the lower body portion 5 and thereby causes a percussive blow to be struck effectively upon the body portion 5, and thus upon the rotary drill bits 8 themselves. It will be realised that the necessary energy for the impacts is imparted to the drill pipes from the rotating drill bits.

In the modified constructional form shown in Figure 4, parts corresponding to the parts in the previously described constructional form are designated by the same reference numerals. In the constructional form shown in Figure 4 the body portion 4 and the body portion 5 are screwed together so that they are effectively integral with one another. The sleeve-like portion within the internal chamber is then separated to form two sleeves 18 and 19,

the sleeve 18 being of non-circular external shape, whilst the sleeve 19 is of circular section. The two contacting surfaces of the sleeves 18 and 19 have circularly extending long wedge-like teeth 20, 21 thereon. A spring 22 bears upon the top of the sleeve 18 as shown. When the drill body is turned, with the drill bits in contact with the surface to be drilled, the drill bits rotate about their axes, and the rotation thereof causes the sleeve 19 to be turned relatively to the drill body. As the sleeve 18 cannot rotate relatively to the drill body, the teeth between the sleeves cause the sleeve 18 to move axially against the action of the spring 22, whereby a series of blows is imparted to the sleeve 19 and thus to the rotary bits. Again it will be apparent that the necessary energy for the impacts is imparted to the spring from the rotating drill bits.

It will be understood that in both constructional forms the long wedge-shape teeth in effect constitute several inclined planes. If desired there need be only one tooth upon each of the co-operating surfaces, such a tooth acting as a single inclined plane.

I claim:

1. For use with a rotary rock drill having at least one rotatable drill pipe, a drill head comprising an upper hollow body part for rotating with said pipe, the upper hollow body part defining a non-circular cavity an inner sleeve member having an upper portion shaped in accordance with the non-circular cavity for axially slidable nonrotatable engagement in said upper body part, a lower co-axial hollow body part rotatably mounted on the lower portion of said sleeve member, a downwardly directed shoulder on said lower body part, a crown on the lower end of said sleeve member which bears upwardly against said shoulder, downwardly directed gear teeth around said crown, a plurality of roller bits carried on said lower part to contact the rock formation, gear teeth around said bits meshing with said crown gear whereby said bits are driven about their axes so as to roll over said rock formation and thereby rotate said lower body part in the same direction as said upper bodypart but at a different speed, and tooth means acting between said body parts to lift the upper body part intermittently away from said lower body part against a force which is constituted mainly by the weight of said pipe and acts to return said upper body part with impacts which are transmitted to the bits. 1

2. For use with a rotary rock drill having at least one rotatable drill pipe; a drill head according to claim 1 in which resilient means in assocaition with said sleeve member is arranged to urge said body parts together.

3. For use with a rotary drill having at least one rotatable drill pipe; a hollow drill body for rotating with said pipe, the hollow body defining a non-circular cavity,

lower co-axial sleeve members mounted within the body, said lower sleeve member being rotatable in relation to the body and said upper sleeve member being shaped in accordance with said non-circular cavity to rotate with the body but being movable axially therein away from said lower sleeve membena gear drive between said rolling bits and said lower sleeve member to effect said relative rotation of the latter, meshing teeth on said upper and lower sleeve members for causing, as a result of said relative rotation, intermittent axial lifting of said upper sleeve member as said teeth move out of mesh, and spring means yieldably resisting said lifting and returning said teeth into mesh with an impact which is transmitted to the bits. I

4. In a rotary rock drill, an outer hollow drill body member defining a chamber, an inn-er concentric sleeve member in the chamber, one of said members being transversely divided to form upper and lower relatively rotatable and axially separable co-axial percussion parts, the non-divided member and the upper part of said divided member mating in the chamber to prevent rotational movement therebetween a plurality of roll-er bits mounted on the lower end of said body member to roll on the surface to be drilled during a drilling operation, said roller bits extending into the chamber for supporting said inner member in said outer member, means to couple a rotary drill pipe to said outer hollow drill body member, cooperating gear means on said roller bits and on the lower part of said divided member whereby the parts of said divided member are relatively rotated at different speeds in the same direction, wedge-like teeth on the facing edges of said parts which co-act during said relative rotation to axially separate said parts at intervals, co-

operating shoulders on said members for limiting said axial separation, and force producing means which resists said axial separation and returns said parts together with impacts which are transmitted to said drill bits.

5. For use with a rotary rock drill having at least one rotatable drill pipe; a drill body according to claim 3;

roller bits carried on the lower end of said body to roll on the ground during a drilling operation, upper and wherein said lower sleeve member is rotated within the drill body through the intermediary of a crown gear on said lower member meshing with gear teeth around said drill bits, the latter being rotated about their axes, when the drill body is rotated due to their contact with the ground.

References Cited in the file of this patent UNITED STATES PATENTS 1,778,966 Stokes Oct. 21, 1930 1,845,074 Billstrom Feb. 16, 1932 1,854,623 Powell Apr. 19, 1932 1,901,513 Harris Mar. 14, 1933 2,072,470 Thompson Mar. 2, 1937 2,153,883 Foster Apr. 11, 1939 

